Synonyms for In the altogether:

adj.

naked (adjective)
in the raw, unclothed, in the buff, raw, peeled.
starkers (adjective)
naked as a jaybird, stark naked.

n.

in the altogether (noun)
stark naked, raw, unclothed, naked as a jaybird, bare-ass, in the raw, in the buff, bare-assed, peeled.